Advice on rear ported speakers "rasping"

Hi,

I am new to this forum and this is my first post. I am wondering if anyone can help me. I have some rear ported Epos M12.2 speakers and prior to that had some Epos ES11s which were also rear ported. I notice an audible "rasping" when I listed to the bass pulses coming out of the rear ports - a kind of "fluttering" sound. Seems to make no difference where the speakers are placed - how near the wall. Has anyone come across this phenomenon themselves - is is normal? Any advice/info much appreciated. Thanks, Phil.

Hi Phil,

Welcome to the forum :)

I'm sorry but I haven't come across your problem before, so perhaps someone else will be able to help you better.

The only questions I would ask are is the "rasping" occurring when playing CD or vinyl, or both? How old are your speakers, and have you checked the drive unit surrounds for signs of wear and/or the bolts securing the drive units to make sure they're as tight as possible?

Marco.

Marco,

Thanks for your reply. The speakers were new this year and have been treated pretty well, although I do play my music at decent volumes! I play both vinyl and CD, but at the moment owing to space limitations I am just using CD. My previous speakers were Epos ES11s, considered somewhat a bookshelf classic, and these seemed to display a similar phenomenon to the new Epos's - the LF pulses coming out of the rear port sound somewhat "phutty" or "rasping" or even like there is a "flutter". I am not sure if this is normal or a fault or even an artifact of my particular system/set up. I would be interested for any other views from Forum members. Thanks! Phil.

Phil.

It might be an idea to ask this question on other forums as well. Ideally you need to find someone with Epos speakers.
Try this one. http://wduk.worldomain.net/

The "phutty sound" you mention could be due to air exiting from relatively small ports, often desribed as a chuffing sound. But i would expect Epos to do better than that.
Of course you may have a very different problem, and it's difficult to describe sounds for other people.
Like Marco said, make sure everything is tight and that there's nothing loose inside.....crossover, terminals, wire etc.

If you had the same with your last speakers, and you have the same amplifier, maybe something has aged(capacitors?) or otherwise become faulty inside.

Thanks alb, There is an Epos forum on the Creek site and I am waiting to gain access. That would appear the best place. I have also e-mailed Epos; Mike Creek often gets back in touch personally.

A mystery this one. I must get round to listing my modest system details, but basically the LF units are driven by original Audiolab 8000M monoblocks which have recently been given an upgrade/service by a fine chap who specialises in servicing Audiolab/Tag gear - Kevin Green (the Audiocellar). P.S I am also currently using a passive pre-amp from a fine founder member of the Forum I believe, Filterlab.

I recently sold a pair of cheap Wharfedale Diamond bookshelf speakers on ebay. They were rear ported and when I tested them they did exactly the same thing - "rasping" from the rear port. There is one particular track which I use to highlight this if anyone can get hold of it to try - Track 5 (Moldavian Triptych) off Donal Lunny's "Coolfin" CD (EAN 7 24349 35422 7). This starts with a long extended LF note and sets my Epos's "rasping" like mad - anyone fancy giving it a go?

Thanks all

Phil

Phil Hi, have you tried putting some foam ( or old socks) loosely in the ports? Keith.

Ports used to augment the bass performance of smaller speakers DO "chuff and whooffff" and even those with drinking straws in can do so too (some Mission 737R's I once owned did this spectacularly). In the case of early Spendor BC1's the port was little more than a hole in the baffle and the sound from this hole was known as a "honk" all at one frequency and gave a lumpy bass with huge distortion, only minimised with certain amps with huge amounts of damping.

The ES11 wasn't too bad as I remember (did they originally have optional grey sponge bungs supplied?). The ES14 was the one. The magority of them had the tongue/phase plug at cone centre and these should be used close to a wall with the sponge bungs IN SITU (or at least placed in sideways). Of course everyone took the sponge out (even when they were stuck in place) and the bloomin' things sounded off like a fog-horn at 80Hz like noones business. Trouble is, people liked it...................

Thanks all...."chuffing" - that's it, thats what they do. To be honest, can't really hear it generally in overall listening, but you can when you listen to the back port. But certain LF notes, like the one on the aforementioned CD, do sound foghornish - a "vibrating, chuffing, fluttering" forghorn. Anyway, your replies have reassured me that it is probably not a fault with the speakers per se - I will wait to see what reply I get from Epos - Mike Creek often replies personally which I find very impressive. Thanks again, Phil.

Glad we could be of some help. Try a bit of fiddling about as per my email, you may just hit upon something good. :) If you do then tell Mike Creek!

Changed my mind, I am sure there is something wrong. Just played some bass heavy Bob Marley and the rasping/chuffing was clearly audible above the music, honking away! I am sure this has got worse and the speakers were new this year! I will be interested to see what Epos/Creek say, but I fear the speakers may be going back!

Anybody else out there had similar problems?

Thanks again,

Phil